A cost accounting method of the Li-ion battery energy storage system for frequency regulation considering the effect of life degradation

The cost of Energy Storage System(ESS)for frequency regulation is difficult to calculate due to battery’s degradation when an ESS is in grid-connected operation.To solve this problem,the influence mechanism of actual operating conditions on the life degradation of Li-ion battery energy storage is analyzed.A control strategy of Li-ion ESS participating in grid frequency regulation is constructed and a cost accounting model for frequency regulation considering the effect of battery life degradation is established.The estimated operating life and annual average cost of the Li-ion ESS under different dead bands and SOC set-points are calculated.The case studies show that the estimated operating life of the Li-ion ESS under the actual operating condition differs significantly from the nominal life provided by the manufacturer under the standard condition and the full discharge mode.This paper provides an accurate costing method for the ESS participating in grid frequency regulation to help the promotion of the ESS to participate in the ancillary service market.

Spatial differences of exergy use of cement manufacturing industry in China based on extended exergy accounting method

Factory-level data from 23 provinces and some national statistical data in cement manufacturing industry and socio-economies in 2012 are used to analyze the spatial distribution of exergy use for China＇s cement manufacturing industry by the Extended Exergy Accounting method. This method takes full account of the inclusion of energy and raw material supply and other external factors （capital, labor and environment） into a comprehensive resource cost assessment. The extended exergy consumption and its intensity quantitatively at the provincial levels of cement production were calculated and then the agglomeration level of exergy use at the regional level was also evaluated. Based on this analysis, their spatial difference in size and efficiency of exergy use at the provincial level were identified. Moreover, their regional characteristics were revealed. Some important results could be drawn as follows. First, the invisible social cost accounted for 1/10 of the total exergy use in cement manufacturing industry, while the energy element shared about 9/10. Second, the gross distribution of exergy use in China＇s cement manufacturing industry was mainly concentrated in the eastern region like Anhui and Shandong provinces, and in the western region like Sichuan province. In terms of exergy use, the coal and electricity were the highest of energy costs in the eastern region, whereas the cost of capital, labor and external environmental factors highlighted the invisible social cost for cement production in the central and western regions to some extent. Third, the efficiency distribution of exergy use in China＇s cement manufacturing industry illustrated an incremental feature from west to east, especially for the energy, labor and capital efficiencies. An evaluation on the environmental efficiency indicated that provinces or regions like Tibet, Xinjiang, Inner Mongolia and Shanxi have undertaken much higher environmental costs. Fourth, the 23 provinces could be classified into eight groups by the Euclidean distance model using the gross and efficiency results of exergy use. Fifth, the high industry concentration degree is the main driving factor of exergy efficiency improvement for cement manufacturing industry in China.

An Accounting Method for Economic Growth

As Chari et al. （2007） indicate, many growth theories explaining frictions in real economies are equivalent to a competitive economy, with some exogenous taxes. Using this idea, I developed an accounting method for identifying fundamental causes of economic growth. A two-sector neoclassical growth model with taxes is used as a prototype economy, and its equilibrium conditions define wedges. These wedges endogenously determine the long run growth rate, which is exogenous and not correlated with any other variables in a one-sector growth model. Furthermore, the importance of wedges in explaining the long-run growth rate can be evaluated through the use of a prototype economy. Applying this method to fifty countries reveals that, among seven wedges, two wedges that are respectively associated with the produc- tion function and the Euler equation for human capital are important in explaining economic growth.

Multi-scale integrated assessment of urban energy use and CO_2 emissions

Accurate and detailed accounting of energy-induced carbon dioxide （CO_2） emis- sions is crucial to the evaluation of pressures on natural resources and the environment, as well as to the assignment of responsibility for emission reductions. However, previous emission inventories were usually productionor consumption-based accounting, and few studies have comprehensively documented the linkages among socio-economic activities and external transaction in urban areas. Therefore, we address this gap in proposing an analytical framework and accounting system with three dimensions of boundaries to comprehensively assess urban energy use and related CO_2 emissions. The analytical framework depicted the input, transformation, transfer and discharge process of the carbon-based （fossil） energy flows through the complex urban ecosystems, and defined the accounting scopes and boundaries on the strength of ＇carbon footprint＇ and ＇urban metabolism＇. The accounting system highlighted the assessment for the transfer and discharge of socio-economic subsystems with different spatial boundaries. Three kinds methods applied to Beijing City explic- itly exhibited the accounting characteristics. Our research firstly suggests that urban carbon-based energy metabolism can be used to analyze the process and structure of urban energy consumption and CO_2 emissions. Secondly, three kinds of accounting methods use different benchmarks to estimate urban energy use and CO_2 emissions with their distinct strength and weakness. Thirdly, the empirical analysis in Beijing City demonstrate that the three kinds of methods are complementary and give different insights to discuss urban energy-induced CO_2 emissions reduction. We deduce a conclusion that carbon reductions responsibility can be assigned in the light of production, consumption and shared responsibility based principles. Overall, from perspective of the industrial and energy restructuring and the residential lifestyle changes, our results shed new light on the analysis on the evolutionary mechanism and pattern of urban energy-induced CO_2 emissions with the combination of three kinds of methods. And the spatial structure adjustment and technical progress provides further elements for consideration about the scenarios of change in urban energy use and CO_2 emissions.